Bantams are very pretty and the eggs are lovely, with a larger proportion of yolk to white than eggs from full-sized hens. However, many bantam breeds are a real pain when they constantly go broody and spend all their time in the nestbox. You then have to remove them and isolate them in the light and open air until their hormones cool down and change back to normal. If you don't do this, they will sit and sit, without bothering to eat or drink enough, and will lose condition by going on longer than the 21 days it takes for a normal hatch. And of course, you won't even get any little eggs whilst all this is going on. Not much fun, if you want active and productive pets! Silkies are the worst, but not the only offenders. Before electric incubators were invented, farmers and gamekeepers used Silkies to hatch out clutches of chicken and pheasant eggs for them, as they were such determined sitters. Many bantams are very lively, good fliers that like to roost in trees in the neighbour's garden given the chance, and can be quite feisty as well.
Some bantams will become very tame, but if you want hens as pets, you may be better suited for a start with some of the larger hybrids that are bred to be calm and friendly in order to live peacefully in crowded conditions in commercial units. And you then get a good daily supply of really excellent eggs, and why not? - children love collecting them and you can really taste the difference. Hybrids come in all sorts of colours, all beautiful, they are bred not to go broody, and if you avoid the flighty Leghorns (sold as White Stars) you can soon tame them. They will probably be less expensive than bantams because they're bred commercially in large numbers, and a good choice is usually available locally. Specialist birds which are bred by small independent producers will usually cost more, and this may be worth it to you if you really want a particular type and know the breeder by reputation, but they probably won't be vaccinated against common diseases like the hybrids will be, and may come from small flocks where inbreeding is a problem, and there may also be incurable residual infections within the flock such as Mareks disease or various bronchial conditions which unfortunately are very common in home-bred birds.

What I'd like are birds that won't completely destroy the garden while free ranging, will become friendly to the point of tame, and that will be safe around children.. And if I was to be completely honest, I do love buff, brown and black colours...

ALL hens will destroy the garden, whatever their size! The little ones are just as good at digging holes, scratching earth and stones over the lawn, and of course pooing everywhere. So you have a choice -Either;
1) Forget about gardening and just enjoy the hens.
Or, 2) you can restrict them to an area you give over to them if you get some chicken netting and poles, so long as you have the sort of hens that won't want to fly out, and if you live in an area where there are no foxes. We have had some terrible stories on here from people whose hens have been taken by urban foxes, some even in broad daylight when the owner was in the garden with them.
Or, 3) like me, you can make them a lovely big enclosed run, with a roof to keep them dry, long perches to sit on and watch the world go by, a big dustbath, willow screening round some of the sides to provide shade and shelter from wind and driving rain, where they will be safe and perfectly happy.

My favourite hybrid is the Columbian Blacktail. Lovely golden-brown feathers and a perky, upstanding black tail, as you would expect. Excellent layers, go on and on, lay beautiful brown eggs. Smaller than many hybrids but the eggs are full sized. You may have seen Duchy blacktail eggs in Waitrose. Apparently, Charles and Camilla have large flocks of them, though how they manage the time to look after them all, with all their other occupations, is beyond me.
The main Poultrykeeper website has a section on chicken breeds, including hybrids - see https://poultrykeeper.com/chicken-breeds/hybrid/

I've just been looking up the hybrids available at my nearest place, and I quite like the look of the Amber Star, Buff Barred, Black Rhode and Sussex Star. All come vaccinated and like you say, are cheaper than the pure breeds...

We do have lots of foxes unfortunately, as our long garden backs onto a railway line.

With that in mind, a big covered run with free ranging time when I'm home (which is a lot of the time).

If you did decide to go with any of your original 3 breeds I would say, in general Perkins are the tamest and friendliest, very good with children, but can be prone to broodiness, Sussex are probably the most productive, they can be broody or not, of average friendliness and orps are something between the 2, prone to being broody, and docile without being particularly friendly.
Whatever you choose, enjoy the experience

It all a matter of opinion B=B, but looking at how you have described your situation and what you are looking to get out of your birds I would say that your instinct of getting bantams is the correct one. Bantams require less space, less feed and a smaller house and you can get virtually every breed in bantam form. They are certainly easier for children to handle than normal sized birds. The birds that are my personal favourites are Thuringian bantams, very friendly and happy to be handled, don't go broody and lay an average of 160 eggs per year though they don't lay in winter. Faverolle and Barnevelder bantams are friendly birds, not terribly broody and lay over winter too. Sourcing these and the bantam versions of other breeds can be more difficult than standard size hybrids but if you are happy to be patient then you ought to be able to find something that takes your fancy by springtime. Keep in mind that keeping chickens in January and February isn't the greatest fun in the world.

Pekins are very good pets and full of character. Yes they can go broody but that's not an insurmountable problem, they aren't as destructive in the garden as some other birds due to their feathered feet and they are as Mrs B says very tame and friendly, I certainly wouldn't rule them out.

Whatever you choose to do I'm sure you will enjoy your birds anyway so don't let the conflicting advice stress you out.

Pekins, Pekins and more Pekins and they are a genuine bantam, not a smaller version of a much larger hen.
They are totally adorable, bright. friendly, extremely good layers of richly yoked cream eggs, mine are still laying now, and are actually not a very
broody lot at all. They live for a number of years, and seem to go on laying for years. My oldest girls are about 5 or 6. I have 10 in all, one cockerel.

They come in every colour imaginable, have glorious fluffy knickers an a very cute waddly walk. They are just the most perfect small hen.